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1970 Duel Carb Whoa's
Hi all, I am new here. After doing some browsing, I still have a big burning question. I just bought my first vintage MB and I can't wait to get it on the road. The car is a 1970 250C which is pretty original besides a repaint many years ago and some obvious home patch work under the hood. I am guessing this is common now that I have begun looking at parts availability and see that many parts have become pretty scarse.
It was purchased as a Southern California survivor car by a collector. It came with all the paperwork including original window sticker. The car is showing 70K miles and according to the previous owner it was road worthy when he got it 7 years ago. Since then it has only left the garage for the annual emissions test to keep it current and registered. He said the carbs were rebuilt shortly after he got it in order to get it threw the smog test and since then it only has required tuning to pass the inspection. He planned to restore it but never started on it, it has just sat all this time. I can't seem to get it to idle. It appears that the front mounted carb is flooding. Is there any recommended updated kits for these cars? I found an article written by a guy who said that he had installed a Webber Kit but I can't seem to find the article anymore. I know from my VW experience that tuning duel carbs is a real pain. How would I go about finding an expert in my area to help me figure out these issues and make her purr like the low milage kitten that she is? Any help would be greatly appreciated. Thanks |
#2
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You might try posting this in the "Vintage" forum...
...and I too am familiar with the hassle of tuning dual carbs...
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2009 ML350 (106K) - Family vehicle 2001 CLK430 Cabriolet (80K) - Wife's car 2005 BMW 645CI (138K) - My daily driver 2016 Mustang (32K) - Daughter's car |
#3
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As a Corvair owner, I too have had the joy of tuning dual carbs. As you get more experienced you will get them sync'ed in no time. They used to see a gauge you could use to check the balance. Basically it was a vacuum gauge with a 'tee' fitting and two lines that you would plug into both carbs.
Before you open the carb to replace the float valve I would try to balance the carbs. The good thing is that these carbs were used by pretty much all the European makes. Any decent Triumph, Alpha, MG, Jag guy can work on them. For parts try going to the MB Classic Center in California.
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"I have no convictions ... I blow with the wind, and the prevailing wind happens to be from Vichy" Current Monika '74 450 SL BrownHilda '79 280SL FoxyCleopatra '99 Chevy Suburban Scarlett 2014 Jeep Cherokee Krystal 2004 Volvo S60 Gone '74 Jeep CJ5 '97 Jeep ZJ Laredo Rudolf ‘86 300SDL Bruno '81 300SD Fritzi '84 BMW '92 Subaru '96 Impala SS '71 Buick GS conv '67 GTO conv '63 Corvair conv '57 Nomad |
#4
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Geeze, I'm glad I'm not around that car with its dueling carbs. I could get shot!
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Regards Warren Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL ENTER > = (HP RPN) Not part of the in-crowd since 1952. |
#5
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Motorcycle shops might still have vacuum carb sync guages.
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Prost! |
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http://shop.ebay.com/items/_W0QQ_dmptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessoriesQQ_sopZ10?_nkw=uni-sync&_sacat=0&_fromfsb=&_trksid=m270.l1313&_odkw=mercedes+113&_osacat=0
This is what we have used for years..with a Cool Whip container inverted to adapt to the Zeniths...works great.
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A Dalton |
#7
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Thanks everyone, I'll try getting them in sync first.
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#8
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there is a tool for that, there is a lot of trick,s air in intake thy should make same sound, ---------1/2.5 turn's 2/adjust to water in glass on bumper untill smoth
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#9
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Quote:
Tool is called the Unisyn. And you DO need the cool whip container..... Jim
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14 E250 BlueTEC black. 45k miles 95 E320 Cabriolet Emerald green 66k miles 94 E320 Cabriolet Emerald green 152k miles 85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles |
#10
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My download
I assume that by "flooding" you mean that you see gas dripping from the front carb's primary nozzle at idle. This can be caused by the carbs being out of balance. What is happening is that the front carb's throttle plate is open a bit more than the rear's, and the resulting higher vacuum is pulling fuel through the nozzle because the idle circuit can't supply enough. So the fix is to balance the carbs to equalize the opening of the throttle plates.
I've been able to get this adjustment done by holding a piece of heater hose the the carbs' throats (by the base), the other end against my ear, and adjusting to make the noise from the air moving the same on both carbs. The trouble with the Unisyn, is that even with the Kool Whip container, it's hard to prevent air leaks and get both carbs to seal equally well against the tool. The flooding can also be caused by a plugged idle circuit or vacuum leaks around the top plate. This sounds like a nice car. If you are going to keep it for a while, I recommend that you do do the Weber conversion. JAM Engineering is one source for a complete kit, or you can piece it together yourself. The car will run much better and you won't spend time and money trying to solve the intractable problems of the Zeniths. I thought the Zeniths were worth the battle until I worked on Jim Freeh's 250C and personally experienced how much better the Webers work. DANTRCAV has some great posts on his battles with the Zeniths.
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Chuck Taylor Falls Church VA '66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe |
#11
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> There are no leaks if you have the correct container..they seal extremely well. which is why we use them.
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A Dalton |
#12
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Thanks for the info, I wanted to look into the Webber conversion so I really appreciate the resource. I am new at the parts hunting for these cars and don't know where to look yet. I want to get it running as it sits just to do it but I am planning on daily driving the car so anything to improve drivability is good.
Anyone have radiator upgrading experience? I can tell that either the radiator or shroud is wrong for the car and it is not going to work this way forever. It is held in by zip ties and has cardboard between the shroud and radiator to keep it from rubbing. YIKES! I was thinking about trying to find a simular sized aluminum radiator and add an electric fan to fix it since the parts seem to be really pricey even in need of rebuild. Any input on this thought would be greatly appreciated aswell. I want to keep it pure but, it's not correct how it is now anyway. I will try to figure out how to post some pics later if anyone is interested. Thanks again |
#13
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Here she is. From what I was told they weren't available in Black so the original owner had it painted when it was only a few years old.
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#14
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Nice car. Brings back memories to my first MB a 1972 250C with the same annoying Zeniths.
Regarding radiator, I think the shroud is bolted with four small bolts (either 8 or 10mm socket size) onto the radiator. It may be that the painter lost the bolts and decided to use zipties to save labor cost... The lower ones are also a bit of a pain to get too. Check your radiator rubber ties as well whether they are good and in place. If not, radiator will hit engine fan occasionally causing interesting tingling sounds from under hood. Bert
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'70 111 280SE/c 3.5 (4 spd manual) - sold '63 MGB '73 MGBGT V8 |
#15
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Niiice
The radiator should slide in and be secured by a rubber ring on either side. The shroud then attaches with small bolts. All IIRC.
Sometimes the motor mounts collapse causing the fan to hit the shroud. This may have happened, and the PO moved the shroud in lieu of replacing the mounts. One thing you should do is get a free EPC subscription, it will help you visualize the parts involved. You will need to put in a credit card number, but it's only for address validation. https://epc.startekinfo.com/epc/home.jsp
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Chuck Taylor Falls Church VA '66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe |
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